New warning: `variable ‘callable’ set but not used [-Wunused-but-set-variable]`

# Bug report

### Bug description:

Popped up in https://github.com/python/cpython/pull/115815 and https://github.com/python/cpython/pull/113674

### CPython versions tested on:

CPython main branch

### Operating systems tested on:

_No response_